Erosion Control

Granting a warranty for long-term erosion control is possible only under certain specified conditions:

• Analysis of site conditions, in particular of slope angle, slope length, soil grain size distribution, micro- and macroclimatic values
• Adaptation of measures to the individual site conditions
• Consideration of the hydrological situation (runoff behavior of the precipitation water, spring and slope waters)
• Use of appropriate plants and additives
• Application of appropriate erosion control agents

Analysis of Site Conditions

With increasing slope angle and slope length, the menace of erosion rises, too. However, sometimes even steep rock or clay acclivities are affected only little by erosion, whereas soils rich in slit and fine sand show serious erosion damages  with only a few slope degrees. Needless to say that the menace of erosion also depends on the climate; humid (rain-laden), mainly inner-tropic zones, but also sparsely covered, arid (dry) zones are specially affected; here, eolian erosion plays an important role, too.

Consideration of the Hydrological Situation

The biggest erosion damages are usually caused by effluent precipitation water (runoff). Thereby, particles of the soil are dissolved and moved down the slope, the water acting as transportation medium. Water can act especially aggressive, where it cannot drain away quickly enough, but flows down the slope and meets easy-to-solve soil particles. This is why coarse-grained soils like coarse and gravel sand as well as coherent soils (clays) are less endangered by erosion. It is not only precipitation water, but also spring and slope waters, which again and again cause landslides and massive gully erosion and badlands. Such site conditions demand for project-individual, completely  specific protecting constructions. Incidental surface and spring waters as well as seeping water ought to be drained off as comprehensively as possible. This is achieved by integrating special drainage systems, drainage trays or drainage ditches.

Adaptation of Measures to the Site Conditions

With increasingly problematic sites, seeding and bioengineering methods become more complicated, complex and expensive. For example, the effective establishing of vegetation on a problematic area with a shallow rootzone, an extreme slope near the perpendicular or dense shadows will only succeed with specific plants and procedures. Surfaces near waters and embankments need very specific reinforcement procedures.

Use of Appropriate Seed Mixtures and Additives

Depending on site and erosion risk, such seeds and additives are selected for planting vegetation, which provide the most comprehensive, long-term and effective erosion control. Mother crops germinate and grow faster, and thus, protect the soil much faster. Certain soil conditioners stabilize the soil aggregates and oppose erosion. Mulch layers protect the surface against heavy rainfall and the energy of water flowing down the surface. Massive and acute risk of erosion, however, usually requires special constructions based on bioengineering applications (see there).

Application of Appropriate Erosion Control Agents

The application of appropriate synthetic-organic tackifiers and soil stabilizers generally results in a sufficient protection against surface erosion lasting for months. Particularly damageable areas - e.g. dike sections endangered by flood waters, steep slopes near roads and railway lines, etc. - ought to be reinforced additionally by specific, rolled erosion control products such as geotextile blankets and mats.